The other day, I ran across some photos of Fawkes' Aerial Swallow, a circa-1910 monorail built on a ranch in what is now Burbank, California. The site where I found the photos, and a couple of others, referred to the Aerial Swallow as America's first monorail. But, in the comments on that post, several people noted earlier examples that put the Swallow to shame.
The photo above, for instance, is a stereoscope image of General LeRoy Stone's Centennial Monorail, which ferried attendees of the 1876 Centennial Exposition between the Agricultural Hall and the Horticultural Hall. (Thanks to Square for linking me to that one!)
Ten years later, another monorail was operating, this time in the Boston area. And unlike the Centennial Monorail or the Swallow, this one really looked like the Fantasy Steampunk Monorail of Dreams.
Look at the wheel configuration! How badass is that?
Invented by Joe V. Meigs, the Boston monorail was designed for a top speed of 20 miles per hour, and to be able round tight corners without disturbing the passengers inside. The train cars themselves were sleek and rounded. The Scientific American article describing Meigs' monorail goes into a lot of explanation about why the rounded shape was clearly mechanically and practically superior, but you kind of get the impression that, even then, everybody just knew that shape made it look more futuristic and awesome.
According to a 1992 article in The Boston Globe, the Meigs monorail failed not because of technical problems, but because of some literally heated competition—Meigs' test line was the victim of arson and vandalism before it was finally shut down in 1894. (Thanks to Rus Gant!)
If you want more info on early monorails in America, I'd recommend checking out this New York Times Magazine story from May 29, 1910. Suggested by Ironic Sans, the article uses several (mostly European) monorails as examples of the different types of monorail one can build.
In conclusion: MONORAIL!